Isobutylene is one of important chemical raw materials which are converted into ethyl tert-butyl ether (ETBE), paraxylene, or methyl methacrylate (MMA) monomer. Of them, for example, a MMA monomer is a substance that is highly useful as a raw material of poly methyl methacrylate useful as a transparent resin. As one of methods for producing this MMA monomer, a method of synthesizing isobutylene as a starting material is mentioned.
Isobutylene as a raw material of the MMA monomer is obtained by extracting isobutylene as tert-butanol through a hydration reaction with an acid catalyst from the spent BB, which is a residue derived by fractional distillation of butadiene from the C4 fraction obtained by naphtha cracking, and then by dehydrating tert-butanol. Further, a method in which methyl tert-butyl ether is synthesized once from isobutylene in the spent BB and methanol and then decomposing this methyl tert-butyl ether is also mentioned. In such a currently used method for producing isobutylene, petroleum is used as a raw material. Therefore, in the circumstance in which there is a concern of depletion problem of petroleum in recent years, a novel method with no dependence on petroleum is desired.
Further, carbon dioxide generated when petroleum is combusted is considered to cause global warming. In this regard, as technologies for producing energy and chemical products from a biomass that is a renewable resource, a biorefinery technology has attracted attention worldwide. Biorefinery means that synthesis gas, sugars such as glucose, aromatic compounds such as lignin, and the like are produced by gasification, glycosylation, and extraction of various biomasses, and these obtained products are variedly converted to produce energy and chemical products. As products produced by biorefinery, as energy, ethanol, butanol, diesel oil, or the like is mentioned. Also for chemical products, according to derivation from a key compound (platform compound) such as sugar-derived succinic acid, 3-hydroxypropionic acid, or asparagine acid, which is suggested by United States Department of Energy, various chemical products can be produced.
Further, it is known that isobutanol can also be produced by fermentation of glucose, and isobutanol is mentioned as one of biomass-derived raw materials. For example, in Patent Literature 1, Patent Literature 2, and Non-Patent Literature 1, it is described that isobutylene can be produced by dehydration of isobutanol.